Corrosion Science Chemistry Research Article | Page 6

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Corrosion: Understanding the Basics
CORROSION
UNIFORM
LOCALIZED
MACROSCOPIC
Galvanic
MICROSCOPIC
Erosion-corrosion
Crevice Intergranular
Pitting Stress-corrosion
cracking
Exfoliation
Corrosion fatigue
Dealloying
Fig. 3 Macroscopic versus microscopic forms of localized corrosion
of corrosion problems. Detailed information on these eight forms of
corrosion can be found in Chapter 4.
Completeness requires further distinction between macroscopically
localized corrosion and microscopic local attack. In the latter case, the
amount of metal dissolved is minute, and considerable damage can oc-
cur before the problem becomes visible to the naked eye. Macroscopic
forms of corrosion affect greater areas of corroded metal and are gener-
ally observable with the naked eye or can be viewed with the aid of a
low-power magnifying device. Figure 3 classifies macroscopic and mi-
croscopic forms of localized corrosion.
Methods to Control Corrosion
There are five primary methods of corrosion control:
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Material selection
Coatings
Inhibitors
Cathodic protection
Design
Each is described briefly here and in more detail in subsequent chapters.
Material Selection
Each metal and alloy has unique and inherent corrosion behavior that
can range from the high resistance of noble metals, for example, gold